1. Field of the Invention
The present invention relates to a braking force regulating structure for a braking device, and more particularly to a braking assembly with self-generating power energy.
2. Description of the Prior Art
A conventional braking assembly, such as the brake for an exercise bike, mainly includes a rotor 1 and a stator 2, as shown in FIG. 3. Two corresponding curved braking plates 3 are pivotally connected to the stator 2, and a plurality of curved permanent magnets 4 are provided at an outer circumferential surface of the curved braking plates 3, such that outer circumferentially surfaces of the curved permanent magnets 4 face toward an inner circumferential surface of the rotor 1 with a proper air clearance left between them. When the rotor 1 rotates, an eddy current is produced as a result of an induction between the permanent magnets 4 and the rotor 1 and consequently, a dragging force will be applied the rotor 1. The smaller the air clearance between the permanent magnets 4 and the rotor 1 is, the stronger the induced eddy current is, and the larger the produced dragging/braking force is. Accordingly, this dragging force can be used as the resistance of sporting equipment.
To regulate the braking force, the conventional braking assembly of FIG. 3 includes a cable 5 that can be manually operated to pull one of two ends of each curved braking plate 3 and thereby adjust a distance of the air clearance between the outer circumferential surfaces of the permanent magnets 4 and the inner circumferential surface of the rotor 1 and accordingly, the braking force of the braking assembly.
Other similar types of conventional braking structures are also found in prior patents. U.S. Pat. No. 6,360,855 discloses a brake for an exercise bike. The brake includes a first and a second disc-shaped plate, a center shaft extended between the two disc-shaped plates, and a plurality of bars and rollers located between the two disc-shaped plates to space the latter from each other by a predetermined distance. The brake also internally includes two curved plates having magnets provided on outer circumferential surfaces thereof. The two curved plates are pivotally connected at an end to and between the two disc-shaped plates, and connected at the other end to a pulling cord. When the pulling cord is pulled, a braking effect of the brake may be changed.
In U.S. Pat. No. 5,711,404, a magnetic adjustable loading device with eddy current is disclosed. In the prior art, the stator is configured by a pair of opposite circular magnetic plates made from magnetic material. The outer rim portion of circular magnetic plate is provided with a permanent magnet, and the inner rim portion of the circular plate is disposed with a biasing spring. The braking force of the magnetic adjustable loading device is adjusted by pulling the free end of the circular plate.
Moreover, U.S. Pat. No. 6,345,703 discloses a magnetic adjustable loading wheel for an exercise apparatus. A stator disk is disposed at the inner side rim of the flywheel and a pair of resilient pieces are mounted on the stator disk. The resilient pieces have a guide post and two pushing posts, and a permanent magnet is fitted on the resilient piece. By means of a pull rope, the clearance between the permanent magnet and a metal conductor at the inner rim of a flywheel is therefore adjustable to change the braking force.
In U.S. Pat. No. 6,273,845, a load applying device for exercisers is disclosed, which includes a plate secured on a spindle, and a rotating disc rotatably secured on the spindle and having a peripheral fence engaged on the plate. One or more arms each supports one or more magnets and each has one end rotatably secured to the plate for moving the magnets toward and away from the peripheral fence of the rotating disc and for adjusting the brake torque of the magnets applied onto the rotating disc. One or more springs may bias the arms and the magnets toward the peripheral fence of the rotating disc.
Furthermore, a wheel-type resistance device for a bicycle exerciser is disclosed in U.S. Pat. No. 5,851,165, which includes a flywheel rotated with a hub member around an axle, and has an accommodation chamber with a first circumferential portion extending in a radial direction and provided with a plurality of magnetically attractive members. A dragging force adjusting member is mounted on the axle and has a second circumferential portion registered with the first circumferential portion. A cam member is mounted rotatably on the axle. A pair of cam followers are disposed respectively on the upper and lower magnetic members and are moved by the cam member such that counterclockwise rotation of the cam member will impart linear movements of the upper and lower magnetic members towards the horizontal line. As such, the overlapping area of the upper and lower magnetic members with the second circumferential portion can be decreased so that the magnetic dragging force can be correspondingly decreased to accommodate a variety of exercising requirements.
A disadvantage of the above-mentioned conventional brakes is that it must be manually operated to regulate the braking force thereof. To change the manually operated brake to a power-controlled brake, it is necessary to connect with an external power source so as to supply power to a driving mechanism of the brake. This requirement restricts the mounting of the brake to a position close to a power supply, otherwise wiring to power source is needed.
Therefore, it is desired to release the conventional brake from the limitations of being mounted close to the external power source, so that the brake may be conveniently used at any place.
To meet the above requirement, there is developed a self-excitation type power-generating braking structure. U.S. Pat. No. 6,084,325 discloses a Brake device with a combination of power-generating and eddy-current magnetic resistance, in which a power-generating coil is provided to one side of a flywheel. When the flywheel rotates, the power-generating coil is caused to generate electrical energy to produce a braking force. However, the power-generating coil must work with the large flywheel to produce the required electrical energy and could not be integrated into the braking device. This results in a complicate structure of the braking device and troublesome assembling and mounting thereof.
It is therefore tried by the inventor to develop a braking assembly with self-generating power energy to eliminate the drawbacks existed in the conventional brakes.
A primary object of the present invention is to provide a braking assembly with self-generating power energy. The braking assembly has power-generating function to provide electric power energy needed by an internal pulling mechanism and an external control panel thereof, so that the braking assembly can be conveniently mounted for use without the need of connecting to an external power supply.
To achieve the above objects, in accordance with the present invention, there is provided a braking assembly with self-generating power energy. The braking assembly with self-generating power energy is provided with a plurality of permanent magnets arranged around a rotary central shaft of the braking assembly to alternate N poles and S poles and at least one power-generating coil on a stator of the braking assembly nearby the permanent magnets for generating an induced electromotive force when the rotary central shaft rotates. A pulling mechanism is provided on the stator for pulling two free ends of two curved braking plates mounted on the stator depending on the induced electromotive force generated by the power-generating coil and thereby regulating a brake force of the braking assembly, and at least one compression spring provided between each of the curved braking plates and the stator to provide a radially outward restoring force to the curved braking plates.